title: Imaging intracellular viscosity of a single cell during photoinduced cell death.
abstract: Diffusion-mediated cellular processes, such as metabolism, signalling and transport, depend on the hydrodynamic properties of the intracellular matrix. Photodynamic therapy, used in the treatment of cancer, relies on the generation of short-lived cytotoxic agents within a cell on irradiation of a drug. The efficacy of this treatment depends on the viscosity of the medium through which the cytotoxic agent must diffuse. Here, spectrally resolved fluorescence measurements of a porphyrin-dimer-based molecular rotor are used to quantify intracellular viscosity changes in single cells. We show that there is a dramatic increase in the viscosity of the immediate environment of the rotor on photoinduced cell death. The effect of this viscosity increase is observed directly in the diffusion-dependent kinetics of the photosensitized formation and decay of a key cytotoxic agent, singlet molecular oxygen. Using these tools, we provide insight into the dynamics of diffusion in cells, which is pertinent to drug delivery, cell signalling and intracellular mass transport.
authors.affiliation: Chemistry Department, Imperial College London, Exhibition Road, London SW7 2AZ, UK. m.kuimova@imperial.ac.uk
authors.forename: Marina K
authors.initials: MK
authors.lastname: Kuimova
authors.forename: Stanley W
authors.initials: SW
authors.lastname: Botchway
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Parker
authors.forename: Milan
authors.initials: M
authors.lastname: Balaz
authors.forename: Hazel A
authors.initials: HA
authors.lastname: Collins
authors.forename: Harry L
authors.initials: HL
authors.lastname: Anderson
authors.forename: Klaus
authors.initials: K
authors.lastname: Suhling
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ogilby
mesh_terms: D000818:Animals; D017209:Apoptosis; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D004058:Diffusion; D019281:Dimerization; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000633:toxicity; D011166:Porphyrins / Q000737:chemistry* / Q000633:toxicity; D026082:Singlet Oxygen / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014783:Viscosity
chemical_list: D005456:Fluorescent Dyes; D017319:Photosensitizing Agents; D011166:Porphyrins; D026082:Singlet Oxygen